Improve byChunk, lockingTextWriter doc

Make byChunk, lockingTextWriter return opaque types (but keep those
types public for backward compatibility).
Add byChunk range example.
Also document that ByLine's primitives can throw StdioException.
Make constructors of std.file.FileException @safe or @trusted
Improve speed of to!string for integral types
Fix Issue 5378 - Make File.byLine accept a string terminator

Add an overload of byLine without a default argument for terminator.
Before, byLine!string tried to instantiate "string terminator = '\n'",
which is invalid.

Note: This removes the default arguments from ByLine.this, but the
constructor was never documented anyway (unlike the range primitives).
Add comments for ranges that are no longer documented
Fix calling ByLine(file) with default args
Ensure terminator string has Char element type
lockingTextWriter should not be a @property
Use ElementEncodingType!Terminator instead of typeof(terminator[0])
Make std.windows.syserror.sysErrorString @trusted
Fix issue 10800
Merge pull request #1466 from Kapps/master

Fix issue 10800
Merge pull request #1462 from tom-tan/trusted-sysErrorString

Make std.windows.syserror.sysErrorString @trusted
Mark a constructor for version(Windows) as @trusted
Make std.file.exists trusted
Merge pull request #1467 from tom-tan/trusted-file-exists

Make std.file.exists trusted
Make std.file.tempDir @trusted
Merge pull request #1458 from ntrel/byLine-crlf

Fix Issue 5378 - Make File.byLine accept a string terminator
Merge pull request #1452 from Kozzi11/toImplForIntegralTypes

Improve speed of to!string for integral types
Merge pull request #1448 from ntrel/stdio-range-doc

Improve byChunk, lockingTextWriter doc